The Grosmont Formation is a

stratigraphic unit A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features ( facies) that characteriz ...

Frasnian The Frasnian is one of two faunal stages in the Late Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Givetian Stage and followed by the Famennian Stage. Major reef-building was under way during ...

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

in the

Western Canadian Sedimentary Basin The Western Canada Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary b ...

. It takes the name from the hamlet of Grosmont, Alberta, and was first described in well Imperial Grosmont No. 1, in 13-17-67-23W4M,

central Alberta Central Alberta is a region located in the Canadian province of Alberta. Central Alberta is the most densely populated rural area in the province. Agriculture and energy are important to the area's economy. Geography Central Alberta is bordered ...

by H.R. Belyea in 1952.

Lithology

The Formation is composed of

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

and dolomite with minor argillaceous dolomite, siltstone and shale.

Anhydrite Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the ...

and anhydritic dolomite occur in the upper part ( Hondo Member) in the west and south. Porous and fractured dolomite is predominant in the eastern extent of the Formation.

Hydrocarbon production

Bitumen Bitumen ( , ) is an immensely viscosity, viscous constituent of petroleum. Depending on its exact composition, it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American Engl ...

is present from the Grosmont Formation in north-eastern Alberta. The Energy Resources Conservation Board of Alberta estimates 406 billion barrels bitumen in place. While most reserves can not be extracted economically with current technology, several production pilots target the Grosmont Formation. The first attempts to produce oil from the Grosmont dates back to the 1970s, when the Alberta Oil Sands Technology and Research Authority and industry partners Union Oil Canada and Chevron Resources Canada conducted an unsuccessful production pilot. Companies currently involved in Grosmont exploration include

Shell Canada Shell Canada Limited () is the principal Canadian subsidiary of British energy major Shell plc and one of Canada's largest integrated oil companies. Exploration and production of oil, natural gas and sulphur is a major part of its business, as ...

Laricina Energy Laricina Energy Ltd. was a private Canadian oil producing company engaged in exploration in North-Eastern Alberta. The company targeted oil sands opportunities outside of the Athabasca mining area and was focusing on ''in situ'' plays in the Gro ...

Athabasca Oil Corporation Athabasca Oil Corporation is a Canadians, Canadian energy company with a focused strategy on the development of thermal and light oil assets. Situated in Alberta's Western Canadian Sedimentary Basin, the company has amassed a significant land bas ...

, OSUM Oilsands Corp,

Husky Energy Husky Energy Inc. was a Canadian company engaged in hydrocarbon exploration, headquartered in Calgary, Alberta, Canada. It operated in Western and Atlantic Canada, the United States and the Asia Pacific region, with upstream and downstream bus ...

and Sunshine Oilsands.

Distribution

The Grosmont Formation occurs mostly in the sub-surface in central and

northern Alberta Northern Alberta is a geographic region located in the Canadian province of Alberta. An informally defined cultural region, the boundaries of Northern Alberta are not fixed. Under some schemes, the region encompasses everything north of the ce ...

. It was observed in outcrop along the

Peace River The Peace River () is a river in Canada that originates in the Rocky Mountains of northern British Columbia and flows to the northeast through northern Alberta. The Peace River joins the Athabasca River in the Peace-Athabasca Delta to form the ...

at Vermilion Chutes at To the east and north, the Grosmont Formation disappears along the pre-

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

erosional edge. Where present, the Grosmont formation is to thick.

Relationship to other units

The Grosmont Formation is conformably overlain by the Nisku Formation of the Winterburn Group or by a thin part of the Ireton Formation (to which it is equivalent in the south). It conformably overlays the Ireton Formation or

Duvernay Formation The Duvernay Formation is a stratigraphic unit of Frasnian Geochronology, age in the Western Canadian Sedimentary Basin. It was first described in well Anglo Canadian Beaverhill Lake No. 2 in Alberta Township System, LSD 11-11-50-17W4M by Imperi ...

. At the

subcrop Subcrop is a term in geology. It is a contrast to the term ''outcrop'', if not a perfect antonym. If rocks exposed at the present-day erosion surface are referred to as outcrops, then now-buried rocks that were exposed at ancient erosion surfaces ...

edge at its northeastern limit it is

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

overlain by the

McMurray Formation The McMurray Formation is a Stratigraphy, stratigraphic unit of Early Cretaceous Geochronology, age (late Barremian to Aptian stage) of the Western Canadian Sedimentary Basin, Western Canada Sedimentary Basin in northeastern Alberta. It takes the ...

of the

Mannville Group The Mannville Group is a stratigraphic unit of Cretaceous age in the Western Canadian Sedimentary Basin. It takes the name from the town of Mannville, Alberta, and was first described in the ''Northwest Mannville 1'' well by A.W. Nauss in 1945. ...

. The lower Grosmont is equivalent to the Mikkwa Formation in

. The entire Grosmont is equivalent to the lower Twin Falls Formation (Alexandra Member) and part of the

Hay River Formation The Hay River Formation is a geologic formation in Northwest Territories. It preserves fossils dating back to the Devonian period. See also * List of fossiliferous stratigraphic units in Northwest Territories This is a list of fossiliferous ...

in the

Northwest Territories The Northwest Territories is a federal Provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2021 census population of 41,070, it is the second-largest and the most populous of Provinces and territorie ...

. The Grosmont Formation is part of the Woodbend Group.

Subdivisions

The Hondo Member is an anhydritic sub-division present in the western and southern extents of the Grosmont Formation.

References

{{Western Canadian Sedimentary Basin, Northeast_Plains=yes Geologic formations of Alberta Frasnian Stage Devonian Alberta Limestone formations of Canada Dolomite formations of Canada Siltstone formations of Canada Shale formations of Canada